Influence of Alimentary Abstinence on Body Burden to Phthalates

Abstract

P-148 Introduction: Human biomonitoring studies have shown by measurements of specific phthalate metabolites in urine that the general population is ubiquitously exposed to phthalates such as DEHP, DINP, DnBP, DiBP and BBzP. Various routes of exposure are possible but oral uptake via diet is suspected to significantly contribute to the phthalate body burden. We know from metabolism studies that 24 hours after oral ingestion of phthalates the major amount of the metabolites is excreted in urine. Therefore, it should be possible to study the contribution of diet on the phthalate body burden by analysing the excretion of the phthalate metabolites in urine over a two-day period of alimentary abstinence. Methods: Three volunteers (2 males, 1 female) aged between 27 and 32 years drank mineral water only, for 48 hours. They collected consecutive urine samples before, during and after the alimentary abstinence (75 urine samples altogether). We determined the excretion of specific urinary metabolites of DEHP, DINP, DnBP, DiBP and BBzP over time by means of HPLC-MS/MS. Results: For the metabolites of DEHP and DINP we detected a pronounced increase in urinary concentrations after the last food intake for all three volunteers directly followed by an apparent and steady decrease within the first 24 hours. Metabolite levels in the samples taken between 24 and 48 hours after the last meal were very low (e.g. 5oxo-MEHP: 1.3–4.0 μg/L; 5OH-MEHP: 1.2–4.3 μg/L) and thus approx. 10- to 20-times below the median values of the general German population. For the metabolites of DnBP, DiBP and BBzP we found no significant effects of alimentary abstinence on metabolite excretion. Levels before, during and after the study in all three volunteers were in the range of the general population. E.g. metabolite levels in the samples taken between 24 and 48 hours after the last meal were 36.7–48.1μg MnBP/L, 9.7–28.1 μg MiBP/L and 2.0–5.6 μg MBzP/L. Discussion and Conclusion: For DEHP and DINP exposure via diet seems to be a major route, with only an incremental share of other routes of uptake. These findings are in accordance with recent studies, where DEHP and DINP were shown to be major contaminants of various fatty foodstuffs. For DnBP, DiBP and BBzP we did not see a causal link between diet and body burden in terms of decreasing concentrations of urinary metabolites after alimentary abstinence. Therefore it is likely that the omnipresent burden with these phthalates has other major routes of uptake, e. g. ingestion of household dust, inhalation or dermal absorption after the use of body care products.